Patent GB-568855-A (GB)
Title: Improvements in or relating to hydraulic controls
IPC: F23K3/00
Filed: 1943-09-06
Abstract: 568,855. Hydraulic clutch-actuating mechanism. STEVENS, A. H. (Steel Proclucts Engineering Co.). Sept. 6. 1943, No. 14562. [Class 80 (ii)] [Also in Group XXX] The time period between successive engagements of a fluid-pressure actuated clutch is controlled by a pressure-fluid timing cylinder having a leakage duct, the rate of discharge therefrom being controllable either manually or automatically. As shown, the mechanism is applied to the actuation of a ram 11 of a stoker for feeding fuel from a hopper 10 into a retort 14. The ram 11 is reciprocated by a crank-shaft 25 driven through a pair of worm and wormwheel gears 63, 64, 60, 61 from a shaft 54. The latter is clutched periodically by a clutch 51 to a continuouslyrunning shaft 34, the clutch 51 being disengaged automatically after each revolution of the shaft 25. The clutch 51 is actuated by a yoke 57 on a shaft 58 which enters the hydraulic control unit 40 and has an arm 90 engaged by a roller 88 on the piston-rod 87 of the clutch-operating piston 86. Pressurefluid generated by a gear pump 70 is led to opposite sides of the piston 86 through ducts 78, 79, controlled by a valve 75 having lands 76, 77, the valve rod passing through the timing cylinder 100 and having slidable thereon a piston 101 pressed by a spring 102 towards a pin 103 on the valve rod. The valve rod has a roller 106 engaging a fork 107 fixed to a shaft 69 which also has an arm 109 with a roller 111 spring-urged against a fixed cam 112. Shaft 69 has a crank-pin 66 which co-operates with a projection 65 on the worm-wheel 64. The land 76 of the valve 75 also controls admission of pressure fluid to a duct 95 leading via a non-return valve 96 and duct 97 to the timing cylinder 100. The latter has a leakage duct 115, Fig. 4, controlled by a valve 116 adjustable by a member 118 either manually or under the action of floating pressure regulators. The right-hand side, Fig. 5, of the piston 101 is always open to exhaust through a port 105. With the parts in the positions shown in Fig. 5, the clutch 51 is engaged and the valve 75 has just been moved to the right by the engagement of the crank 66 with the pin 65 on the worm-wheel 64 which is just finishing one complete revolution. Pressure fluid will now pass through duct 79 and move the clutch piston 86 to the left and disengage the clutch. The timing cylinder has previously been charged with pressure fluid. This fluid now slowly escapes through the leak duct 115. When the pressure drops sufficiently, the spring 102 moves the valve 75 to the left, the valve 75 snapping rapidly to its end position due to the engagement of the roller 111 with the overcentre cam 112. Pressure fluid is thus again fed to the timing cylinder 100 and to the lefthand side of the piston 86. The piston 101 then moves along the rod 75 away from the stop pin 103 to compress the spring 102 and when the pressure has built up in the cylinders 85, 100, the piston 86 is forced to the right to engage the clutch 51. The ram 11 thereupon makes a double stroke, after which the projection 65 engages the crank 66 and moves the valve 75 to the right to redisengage the clutch 51. A preselector valve 80 having three sets of ducts 125 ... 130, Figs. 7-9 (not shown), may be provided adjacent the ducts 78, 79. The valve 80 may be set in any one of three positions. In one position it enables the apparatus to function as above described, under the control of the timing cylinder 100. The second and third positions result in permanently engaged and disengaged positions respectively of the clutch 51. In the fuel feeding device shown, a lever system 16, 17 in the fuel hopper 10 is connected to the ram 11 so that movements of the levers facilitate downward movement of the fuel.